Concrete is one of the most widely used materials in the world, and with good reason. It’s strong, durable, and versatile. However, concrete is also a major source of pollution, thanks to the production of cement, which is a key ingredient in concrete. Fortunately, concrete can be recycled and reused, which helps to reduce its environmental impact. When concrete is recycled, the old concrete is crushed and used as aggregate in new concrete. This not only reduces the need for new raw materials, but it also cuts down on emissions from the production of cement.
In addition, recycling concrete can help to save energy and reduce waste. So if you’re looking for a way to be more environmentally friendly, consider recycling your old concrete. It’s good for the planet and it might just save you some money too.
The world loves concrete. We create an enormous amount of it. In fact, we produce 10 billion tonnes of it every year. That is one whole cubic metre of concrete for every man, woman and child on the planet. Every year! Over the next 40 years we expect to produce 230 billion square meters of concrete. That adds about the same construction as the whole of Paris every week for the next 40 years.
As old concrete crumbles through time and wear, then it must be replaced, but what do we do with all that old concrete? We produce 900 million tons of concrete waste each year. The shameful thing is that 83% of that is dumped into landfill sites never to be used for anything useful ever again. Is this the right thing to do? Surely not.
Why throwing away old concrete is a bad idea.
Firstly, it costs money. Getting rid of old concrete to a landfill site costs approximately $35 per tonne. That could add up to a large demolition job. In many countries, recycling centres will pick up used concrete for free.
Perhaps more importantly is the fact that making concrete is bad for the environment. Two thirds of concrete is aggregated and that is usually mined from the ground. In the US alone that amounts to 1.96 billion tons of aggregate, 10 metric tons for every man, woman and child in the country. Aside from the damage to natural landscapes, vast quantities of fossil fuels are used in mining, construction and mixing.
What can we do with old concrete?
Well we can recycle old concrete to make new concrete! Old concrete can be processed to produce aggregates that can be used alongside traditional excavated aggregates. Unfortunately, using 100% recycled concrete as aggregate doesn’t make good concrete. It is less durable and decays easily. However, a mix of 35% recycled concrete and 65% excavated aggregate makes very good concrete indeed.
Now, we know that about 70% of concrete is aggregated and we use around 7 billion tones (70% of 10 billion tonnes of new concrete) each year. Given that we throw away 750 million tonnes of concrete each year then there is space to recycle every single bit it and reduce the demand for fresh aggregate by that same 750 million tonnes and still have space to use more.
How do we recycle concrete
It is relatively simple to recycle concrete. The concrete is crushed and smashed using mechanical crushers and impactors. Magnets are used to remove any metal from the crushed concrete. The resultant rubble is then washed and graded for use to produce different types of aggregate for remixing to make new concrete.
Benefits of recycling concrete
Recycling concrete reduces the demand for fresh aggregate and extends the life of landfill sites.
In many countries standards exist, like LEED, to certify that the company is fulfilling environmental requirements in the conduct of its construction work. Using recycled concrete will score points for this type of evaluation.
Using recycled concrete reduces the cost of aggregates and so money is saved.
Tests like those performed by the University of British Columbia Engineering Department in a five year study demonstrate that using recycled concrete as 35% of the aggregate has no detrimental effect on the concrete. In fact, the concrete produced is lighter than normal concrete and can be used effectively in the construction of buildings.
Here at BECOSAN we know that using recycled concrete as the aggregate in new concrete is good for the purse strings and good for the planet. We also know that concrete floors made using recycled concrete can also be made to look good too. The BECOSAN treatment of grinding, densifying and polishing concrete can create a floor that will match any floor made with traditional aggregate.